1. Field of the Invention
The invention relates to the field of security and, more particularly, to the use of speech recognition to provide security functions.
2. Description of the Related Art
Electronic home security systems have been available to consumers for many years. Typically these systems are micro-processor-based, and include a variety of sensors, such as photo detectors, motion detectors, and sound detectors. In normal operation, these standalone systems monitor the sensors to detect unusual or suspicious events, such as a discontinuity in the input data stream that rises above a certain threshold. Such a discontinuity could result from a window breaking or loud footsteps, which could indicate that an intruder has entered the monitored area. However, the high cost of these systems, the extensive installation required, as well as the proliferation of personal computers (PCs), have given rise to home security systems which can be implemented as software programs running on commercially available PCs.
PC-based home security systems typically include input devices, such as microphones and/or a video cameras, which are directly attached to the PC. As is well known in the art, these systems essentially listen and watch through the microphone and/or video camera for significant changes to the normal background environment of the house, such as a sharp rise in the overall sound level within the home above some threshold sound level or a rapid change from dark to light within the home. Upon determining that the significant change is of an unusual or suspicious nature, the system can take appropriate remedial action, such as calling a fax machine and sending a fax-based message, or broadcasting a voice message over a modem.
One disadvantage of existing PC-based alarm systems is the inherent susceptibility to nuisance tripping and false alarms. That is, these systems normally rely on complex and cumbersome algorithms and metric tables to determine whether the significant change warrants any remedial action. It is difficult, if not impossible, however, to anticipate every sound that may be interpreted as a suspicious event. For example, a neighbor's window breaking or construction noise outside the house being monitored could cause an alarm message to be sent to a police station. Although more sophisticated PC-based alarm systems can be configured to monitor the environment for a period of time in order to create a model of a typical environment during a certain time of the day, these systems require continual calibration as the environment changes.
Accordingly, there is a need to develop improved alarm and/or sound detection systems.